This invention relates to a new sensor and associated method for detecting the presence of specific chemical entities even at extremely low concentrations. Particularly, it is applicable to the detection of one component of a receptor/binder pair, typically an antibody/antigen pair.
Heretofore, many methods and devices have been disclosed for the detection of chemical entities such as antibodies and/or antigens. These include systems based upon a field effect transistor with a gate region modified to detect a biochemical contaminant. See, e.g., U.S. Pat. Nos. 4,238,757 and 4,273,636. Other systems detect biochemical agents based on surface changes in a hydrophobic membrane upon adsorption of an antigen (U.S. Pat. Nos. 3,966,580 and 4,151,049); changes in an electrochemical cell having one electrode which is immunochemically active (U.S. Pat. No. 3,403,081); changes in the capacitance of a system having an immunochemically active electrode (U.S. Pat. No. 4,072,576); as well as more classical methods, see, e.g., U.S. Pat. No. 4,278,652.
All of these methods are deficient from various points of view. For example, none address the often difficult problem of non-specific binding of the species of interest. This is especially exacerbating when only a low signal to noise ratio is available either due to detector insensitivity or a very low concentration of unknown species. Furthermore, many of the prior art techniques are not adaptable to liquid and gaseous samples.